Tunnel safety

The Clem7 tunnel clearance height is 4.6 metres.

If you drive a vehicle over this height you won't be able to use the tunnels. Detection systems outside the tunnel notify drivers of height limits. Warning signals are initialised if the height limit is breached. All vehicles exceeding the height limit will be advised to take an alternate route.

If drivers of overheight vehicles proceed, entry will be prevented by an overheight barrier structure.

We also monitor the internal and external air quality of the tunnel. Air quality monitors in and outside the tunnel constantly measure the presence of carbon monoxide (CO), nitrogen dioxide (NO2), fine particles and visibility levels.